It suddenly became apparent that a new profession was in the making.Īutomobile service technicians maintain and repair cars, vans, small trucks and other vehicles. People were not only unskilled in driving but also were ignorant of the basic maintenance and service the automobile required. With the ill-prepared roads suddenly overrun by inexperienced drivers, accidents and breakdowns became common. The “Big Three” (Ford, GM and Chrysler) automobile makers produced millions of cars for a public eager for freedom and mobility the automobile promised. Translate this extract in written form:Īs automobiles changed through the years, mechanics or automobile service technicians, as they are now called, have kept them running. This forces the burnt gases out of the engine.Ĩ. At the same time, the piston moves up towards it. This helps the gases to expand rapidly after ignition.Į) The cam pushes the exhaust valve down. Soon afterwards, it puts the fuel under high pressure. This sucks the fuel in.ĭ) The piston moves up towards the valves. Immediately after this, it creates a vacuum in the cylinder. This allows the fuel to enter the cylinder.Ĭ) The piston moves away from the valve. Simultaneously, the cam pushes the intake valve downwards. This makes the piston move down with great force.ī) The camshaft rotates. Immediately afterwards, there is an explosion. – As the piston moves up, the exhaust valve opens, which lets the burnt gases escape.Ī) The spark plug ignites the fuel. At the same time, the exhaust valve opens. Now join each group into a single sentence. When / As the brake pedal is pressed, the piston pushes the oil along the brake pipe.) When or as can sometimes be used with the same meaning when it’s difficult to decide if two actions are simultaneous or in rapid sequence. As the piston moves up, it compresses the fuel.) When the spark plug ignites, the gases explode.)Īs often indicates that two actions happen simultaneously, both at the same time. When often indicates that two actions happen in sequence, immediately after the other. The cycle is repeated thousands of times per minute. This opens the exhaust port and the burnt gases are pushed out. At the same time, the cam above the exhaust valve pushes the valve downwards. As the crankshaft rotates, it pushes the piston up the cylinder. This makes the crankshaft rotate and provides torsion to drive the wheels of the vehicle.Įxhaust stroke. Immediately after this, the gases expand in the cylinder, which pushes the piston downwards. The compressed fuel is ignited by the spark plug and there is a small explosion at the top of the cylinder. As the piston moves up towards the valves, it compresses the fuel. Simultaneously, the cam above the intake valve rotates and allows it to close. As the crankshaft rotates, it makes the piston move up the chamber towards the valves. As the piston moves down, fuel is sucked into the cylinder through this inlet.Ĭompression stroke. This makes the valve move downwards, which opens the intake port. At the same time, the cam above the intake valve rotates. This makes the piston move down the cylinder, away from the valves. Here the piston is furthest away from the crankshaft. The cycle begins at top dead centre (TDC).
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